刈取後の再生過程から, ラジノ・クローバーの乾物生産に及ぼす温度の影響をみてきた結果, 乾物生産量は20℃が最も多く, 25℃, 15℃の順に少なくなり, 30℃ではとくに著減し, 明らかに夏枯れの様相を呈することがわかつた. 再生過程における温度の相違によるこのような乾物生産量の差異を同化器官の形態形成を中心として, これと再生過程の温度との関係から検討した結果, 次のことが明らかにされた. (i) 再生初期では, 温度が高いほど葉面積の拡大は旺盛であり, 低温区ほど低調であるが, 中期から後期にかけては漸次低温のものが旺盛となつてくる. そして高温のものほどより早期に葉面積の拡大が衰退してくる. (ii) 総葉面積の大小には葉数と平均1葉の大きさとが関係するが, 再生過程では, 葉面積の消長に対して常に葉の発生数が先行していることがわかつた. (iii) 再生の後期における葉の枯れ上りは, 温度が高いほど, また時期の進むほど多くなるのがみられた.

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To understand the causal relationships of growth retardation of Ladino clover caused by high temperature during summer, studies on the influences of high temperature upon photosynthesis, respiration, chemical composition and regrowth of the plant were carried out. Obtained results are as follows : 1) During regrowing process storone and root of the plant play a role as storage orgran. The former plays a role as primary storage organ and the latter as secondary one. 2) The relationships mentioned above fit not only the case of carbohydrates reserves but also nitrogen compounds. 3) In lower temperature plots, plant uses to some extent carbohydrates and nitrogen compounds reserved in storage organ during the first half of regrowth, but reserves them again during the latter half of regrowth. On the other hand, in higher temperature plots, plant uses the greater part of them during the first half of regrowth, and the amount of reservation during the latter half of regrowth, and the amount of reservation during the latter half of regrowth is lesser than that of the lower temperature plots. 4) The reasons to make the regrowth of plant in higher temperature plots worse are as follows : (1) decrease of emergences of leaves (2) promotion of aging of leaf blades (3) reduction of photosynthetic capacity affected by reduction of leaf area expansion capacity (4) increasing of respiration affected by high temperature and reduction of photosynthesis / respiration ratio decrease the dry matter production (5) decrease of nitrogen compounds contained in storage organ with advancement of regrowth. 5) Conclusively, two causes bringing about growth retardation of Ladino clover grown under higher temperature were deduced. The one is increase of respiration affected by high tempreature, the other promotion of aging of leaf blades.

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In the researches conducted so far on the formation of the root system of leguminous plants, stress has been placed, in most cases, on the study of how the roots spread underground. Consequently, the characteristics of root systems have been defined by a mere term of "the shallow-root type" or "the deep-root type." This study is different from the previous researches. That is, the study attaches importance not so much to the spreading condition of the root system as to the clarification of the characteristics observed in the developing process of branch roots. The purpose of the study is thus to find out a law of nature governing the growth of the root system, and, on this basis, to classify the root system in a new way. The experiment was conducted during the period from the autumn of 1960 to the summer of 1963. The varieties used in the experiment were as follows: Alfalfa (Atlantic) Common vetch Red clover Broad bean Ladino clover Chinese milk vetch Egyptian clover Soy bean (Hogyoku) Sweet clover Lupine (Yellow flower) Cowpea The results obtained were as follows: 1) As for the root system formation, it was observed that the main root began to grow first, and then branches of the first order started to grow from its base and extended toward the root apex (see Fig. 1). This phenomenon is common to all the specimen plants. 2) It was made clear that, as the plants grew, their root systems transformed from the uniform standard type to the following three different types according to their varieties: a. Alfalfa type b. Vetch type c. Intermediate type 3) Alfalfa type Fig. 2 is a schematic diagram showing the process of this type of root system. The main root (0) grows first, and the first-order branches (a₁, a₂, ……a₈) appears from its base and extend toward the root apex one after another (Standard type). But subsequently, the second group of first-order branches (b₁, b₂, ……b₆) begin to develop. Following their development, te subsequent groups of (c₁, c₂, ……c₄) and (d₁, d₂) begin to take shape. This process of development is repeated at regular intervals. a) In the case of alfalfa, the development of first-order branches took place 4 to 5 times by the time when the plant began to blossom. b) The type of characteristics observed during the development of first-order branches were observable also in the case of branches of the second and third orders. c) It was interesting to note that the primodium of the subsequent first-order branches (such as b₁, c₁ and d₁) appeared, as a rule, side by side with the initial branches (a). d) These characteristics were observed in the case of alfalfe, Chinese milk vetch, red clover, ladino clover and the like. e) These characteristics were not affected by soil conditions or reaping methods. 4. Vetch type This type of plant is far simpler than the alfalfa type in characteristics. That is, once first-order branches grow at the base of the main root and extend the root apex, no similar branches appear any more. Common vetches belonging to vicia group, broad beans and cowpeas presented this phenomenon. (See Fig. 4) 5. Intermediate type This type can be regarded as standing halfway between the alfalfa and vetch types. It is also conceivable, however, that this type originally belongs to the alfalfa or vetch type but none the less presents the characteristics peculiar to the "intermediate type" depending on the conditions surrounding the roots. In the author's experiment, soy beans and yellow lupines presented such characteristics.

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Diurnal changes in the photosynthesis and respiration of nine forage crops were determined under two different temperature levels, 15 and 30°C, enviromental factors including light intensity being kept constant. The followin results were obtained : 1). Under both temperatures, two types were observed of the diurnal changes in photosynthetic activity, one of which did not show any change throughout day and night and the other showed some decrease during the night hours. In any species, so-called "midday depression" was not seen. 2). The changes in photosynthesic activity, if they did occur, took place at the same time, though they failed in most cases to show the ordinary, clear-cut pattern of diurnal changes. 3). Depending on species, the following three groups were distinguished of the eflect of temperature on diurnal changes in photosynthesis : (a). Those, such as Italian ryegrass, red clover, orchard grass and rye, non-sensitive both to temperature levels and to other conditions, remaining unchanged in their photosynthesis throughout day and night. (b). Those, such as Dallisgrass, Sudangrass and new sorgo, sensitive to temperature, showing little change in photosynthesis when the temperature level fell within the optimum temperature range for their photosynthesis, but showing depression in photosynthesis, when the temperature level fell beyond the optimum range. (c). Those, such as teosinte and common vetch, more sensitive to some factors other than temperature level, showing depression in photosynthesis during the night hours under both temperature levels. 4). In all species tested, respiration under both temperature levels. showed a gradual decrease as time passed by.

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頴花が分化発達し, 授精し, 稔実する過程における各部の澱粉の消長を検鏡により観察した. (1) 頴花各部のうち, 小穂軸, 子房壁, 盤状体等はその分化, 伸長, 成熟の過程において, 待機澱粉の蓄積, 消費および移動澱粉の再蓄積, 消失という稲の栄養体柔組織に普遍的な過程をたどつた. しかしその他の大部分の部位あるいは器官では待機澱粉を蓄積しなかつた. (2) 葯においては花粉母細胞分裂前transitory tissueに蓄積しいた澱粉が小胞子形成期には消失した. 以後開花直前の花粉に多量に蓄積する外は葯各部に澱粉はほとんど認められなかつた. (3) 子房壁の澱粉粒は授精直後から形成され始め次第にその大きさを増し, 授精10日頃から消失し始め2週間目には完全に消失した. (4) 珠心は授精3～4日目に崩壊を始め, 含有澱粉も消失する. 5日目には背軸維管束近辺を除いてほとんど崩壊吸収された. (5) 胚乳細胞においては, 他の栄養体柔組織におけるものと明らかに形の異なる特徴ある複粒澱粉を授精5日目に一斉に蓄積し始め, 以後稔実終了までその大きさを増加する. (6) 胚においても早く分化成熟する部位ほど大形の澱粉粒を蓄積する傾向があり, 胚盤には特に大形の澱粉が含有され, 次いで幼根の若い導管細胞のものが大きかつた. (7) 解剖学的観察から, 胚乳および胚に対する養分の径路として背軸維管束→珠心表皮, 背軸維管束→珠心突出部の二つの道を想定した.

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水稲の生育時期別に遮光, 葉身切除, 少肥料, 過高地温等の生育を阻害する条件を与え, その後の回復過程と組織内澱粉消長とを観察し次の結果を得た. (1) 悪条件が幼穂形成前に終了する処理では一時的に生長が抑制されるが, その回復過程で葉身面積の拡大, 茎や根の新生を活発に行ない, 通常稲体が次第に老化の過程に入る穂の形成中に於て, 体内生理がいわば若返った状態に保たれ, 大きい穂の形成, 乾物増加率の増大を来たし, 籾生産も増加する可能性が見られた. (2) 悪条件が幼穂形成以降穂のの発達期間に作用する場合には乾物生産も籾生産も著しく低下する. (3) 悪条件から回復する過程で一時的に不足する炭水化物の給源になるのは稈, 葉鞘に蓄えられていた移動澱粉で, これが糖に変化して直接体内生理に参加する. (4) 幼穂形成前の処理では葉数を増す場合が多いが生理の若返りと共に注目すべき現象である.

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Crystalline materiales contained in the juices of flowering induced plants such as vernalized radish and shortdayed cocklebur were analysed by the x-ray diffractometer, geigerflex, and the constituents of flower regulating factors were discussed in this paper. In the case of radish, two kinds of juices were obtained from the fresh tops of both vernalized-longdayed radish seedlings and the nonvernalized-longdayed. As to the of cocklebur, the one was obtained from the absolutely longdayed plants and the other two juices were squeezed from the plants treated with 10 and 28 days' short photoperiods. The apparent difference between the check and the flowering induced plants was observed in both cases of radish and cocklebur, comparing with the diagrammatic results recorded by the x-ray diffractometer. It may be considered that a certain crystalline substance exists in the flowering non-induced plants, but some other crystalline substance dominates in the flowering induced plants. The former would play as the inhibitor, and the latter would play as the promotor in the flowering mechanism.

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How to increase the amount of photosynthetic products per unit land area in the growth period after heading under luxuriant growth conditions is the most serious problem in maximizing yield in rice cultivation. As increasing the light-receiving efficiency after heading by controlling the growth of rice plants was considered to be a new approach to the problem, the authors therefore examined the relation between morphological characteristics (the form of plant) and the photosynthetic efficiency of rice plants. The main points of the results may be summarized as follows. 1. Under sufficient light intensities no difference was found in photosynthetic effciency between a leaf-blade placed at a right angle to the sunlight and that placed horizontally, and a little difference was found between a leaf-blade at a right angle and that placed parallel to the sunlight (cf. Table 1). 2. No difference was found in photosynthetic activity between the obverse of a leaf-blade and the reverse of it (cf. Table 2). 3. Permeant sunlight which had passed through a leaf-blade was of no use on photosythesis (cf. Table 4). 4. The photosynthetic efficiency of a leaf-blade was always lower when it was curved than when it was straight, and the fact was more clearly observed when a comparison was made between plants or plant communities whose leaf-blades were curved and those whose leaf-blades were straight (cf. Table 3 & 6). 5. In case of the leaf-area being equal with each other, a plant with leaf-blades which are short in length and large in number was much higher in photosynthetic efficiency than that with leafblades which are long in length and small in number (cf. Table 7). 6. On the basis of the above mentioned facts, it was suggested that (1) leaf-blades of the ideal plant should be erect, straight and short in length and large in number, and (2) the type of the ideal plant should be heavy tillering so that the plant may increase light-receiving efficiency. 7. Judging from the photosynthetic efficiency, the percentage of ripened grains and the grain yield in actual paddy fieid, an optimum leaf-area index at heading stage was nearly 6.5 to 7.5. However, taking the resistance of plants against lodging, diseases and pests into account, 6.0 seemed to be optimum (cf. Fig. 2 & 5). 8. From the results of photosynthetic efficiency in actual fields, under luxurious growth conditions the most efficient form of rice plants in photosynthetic efficiency in the period after heading was likely to be progessively short in the length of leaf-blades from the 4 th or 3 rd leaf from above up to the upper-most leaf as the position of leaves on a stem goes up (cf. Fig. 4).

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In the previous paper (LXVII) the authors proposed the characteristics of the "ideal plant" and demonstrated through the "ideal plant" the possibility for obtatning 10.2 tons per hectare of brown rice, which was much higher than the yield of the first prize in the competition of maximizing yield in 1962 in Japan. In the present paper the authors furthermore tried to improve the method along the same line as shown in the previous paper, adding two other varieties, a narrower spacing, an earlier and a later planting treatment. Unfortunately, in 1963 the weather condition in the tillering stage was much worse than usual and it caused the plant to emerge less tillers and longer leaf-blades than those in 1962, in other words it made the plant grow somewhat in opposition to the characteristics of the "ideal plant". And, to make the matter worse, the weather condition in the ripening stage was also much worse than usual, so the percentage of ripened grains was much reduced by it. As a result of it, the yields of brown rice in 1963 ranged from 5.2 tons to 7.5 tons per hectare. A noteworthy fact, however, was observed in this experiment, i. e., the treatment No. 7 which was transplanted at the end of June obtained as much as 7.5 tons per hectare in yield of brown rice. (In general in Japan the rice plants transplanted at the end of June is less by 20 to 40% in yield than those transplanted in early May. And in 1963 the weather condition at the ripening stage of the latest transplanted treatment was a little bit better than those in earlier transplanted treatments.) This fact was considered to reconfirm the truth of the principle for maximizing yield by controlling the growth of plants aiming at the "ideal plant".

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Combining 4 classes of air-temperature (36, 31, 21 and 16°C) with 4 classes of water-temperature (36, 31, 21 and 16°C) to give 16 different factorial conditions, and subjecting rice plants to these different conditions for a 15-day period at different stages of growth under natural sunlight, the authors examined the combined effects of air- and water-temperature on the grain yield and its components. The variety used is Norin No. 25, a mid-term variety. The results may be summarized as follows : 1. In the early growth period (Stage I and II, cf. Table 1), only water-temper-ature has a remarkable effect and air-temperature has no effect on yield, i. e. a water-temperature of 31°C always has the most favourable effect and that of 21°C has the second most favourable effect, while that of 16°C has the most unfavourable effect on yield under any air-temperatures (cf. Table. 2). 2. In the middle growth period (Stage III and IV), both air-temperature and water-temperature have serious effects on yield, i. e. under any water-temperatures an air-temperature of 31°C increases yield most, while that of 16°C decreases most, and under most air-temperatures a water-temperature of 31°C increases yield most, but under some other air-temperatures a water-temperature of 21°C increases most (cf. Table. 2). 3. In the late growth period (Stage V and VI), only air-temerature has a remarkable effect, while water-temerature has no effect on yield, an air-temperature of 21°C having the most favourable effect on yield. At the Stage V a remarkable detrimental effect of a high temperature of 36°C as well as that of a low temperature of 16°C is found on yield, but at the Stage VI a low temperature as low as 16°C has a beneficial effect on yield and high temperatures such as 36°C and 31°C have remarkable detrimental effects on yield (cf. Table. 2). 4. It has also been confirmed from the results of the present experiment that the influences of air-temperature and water-temperature which increase the yield positively can act only up to the spikelet initiation stage, in particular they act most at the initial stage of panicle differentiation, and after that stage only the influences which can prevent a reduction in yield can act. It has therefore been made clear that the importance of water-temperature in increasing yield in the early growth period as well as the seriousness of the detrimental effect of high air-temperature on yield in the late growth period cannot be over-emphasized. 5. The above mentioned facts are reasonably supported by the responses of yield-components to air- and water-temperature in different stages of growth (cf. Table. 2). 6. The main reason why the grain yield and its compents are strongly influenced by only water-temperature in the early growth period (up to the necknode initiation stage), by both air-temperature and water-temperature in the middle growth period (from the neck-node initiation stage up to the final stage of reduction division) and by only air-temperature in the late growth period can likely be ascribed to the fact that all the growing points of rice plants are always below the surface of water during the early growth period, and some of them are located above the water-surface and some of them still below the water-surface during the middle growth period, while all of them are definitely located above the water-surface in the late growth period.

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A close, negative correlation was found between the mean prefectural yield of paddy rice and the mean daily air temperature during the Aug. -Sept. period which roughly corresponds to the "substantial yield production period". On the other hand, there was a positive, linear correlation observed between the yield and the mean daily amount of solar radiation during the same period among northern prefectures, although there was no correlation found between the two when southern prefectures were included. However, this was interpreted not as a proof to show the absence of the effect of solar radiation, but as a result of disturbance of its effect by the adverse effect of air temperature in warmar regions. Assuming, therefore, that the solar radiation effect to be always proportional, a parabolic function, f(t), which has a maximum at t=21.5°C, was derived to fit the temperature-yield relationship. Further, by combinating the solar radiation effect, s, with the former, a function, sf(t), has been obtained to express the "climatic productivity" of each prefecture. Quite a high correlation coefficient at a higher level than 0.1%, was shown to exist between the climatic productivity index thus calculated and the rice yield among all the prefectures. From these, it has been concluded that both the mean daily air temperature and the mean daily solar radiation during the Aug.-Sept. period play an important role in determining the local differences in the productivity of paddy rice in Japan. Some probable causes for this were discussed in relation to photosynthesis and dry matter production.

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The germination (emergence) of one wild species and four cultivated variety barnyardgrass seeds was examined under the different soil conditions. The results obtained are as follows: 1. Any difference of the velocity of germination could not be found between 60% soil moisture (by weight) plot and moistened plot to soil capacity. But the velocity was recognized to be decreased with the depth of irrigation. At the early stage of germination period, the remarkable decrease of velocity was not caused by the low daily mean soil temperature but by the irrigation. But, the reverse relationship of the decrease observed latter was thought to be mainly based on the slight rising of the daily mean soil temperature and the increased amount of the accumulated daily mean soil temperature during several days. On the other hand, the decrease of velocity by the application of inorganic fertilizer on the non-irrigated plots was slight. But, the application on the irrigated plots caused the comparatively great decrease and especially remarkable decrease in the irrigated low soil temperature plots. As the results of these, the velocity with the application of inorganic fertilizer resulted in the slight decrease. Except very late variety Daruma showing specially great decrease of germination velocity due to irrigation, low soil temperature and application of inorganic fertilizer, there was no relationships between the velocity of germination of any variety and the heading date. 2. The greatest decrease of germination percentage was caused by the irrigation and the decrease by the application of inorganic fertilizer was not so remarkable. Moreover, the decrease by the low soil temperature was very slight. The decrease of the germination percentage caused by the application of ammonium sulphate was greater than the case of ammonium nitrate. As to the non-irrigated plots, the arrangement of plots in sequence from the low soil temperature plot without any application of fertilizer showing the highest germination percentage, is as follows; the low soil temperature plot with application of inorganic fertilizer, the high soil temperature plot with the application and the high ones without any application. As to the irrigated plots, the arrangement of plots in sequence from the high soil temperature plot without any application of fertilizer showing the highest germination percentage, is as follows; the low soil temperature plot without any application, the high ones with the application and the low ones with the application. The decreasing effect of germination percentages due to irrigation, soil temperature and application of inorganic fertilizer was found to be differed with materials.

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印度稲の葉面当り光合成能力を, 人工光下切断葉について通気法で測定し, 内外の要因と光合成能力との関係を検討した. 実験はすべてセイロン国において行なわれ, 次のような結果を得た. (1) 光-同化曲線の形および光飽和点は, 日本稲の場合と同様で, 飽和光度は40～50luxであつた. (2) 印度稲の光合成能力に対する適温域は25～35℃の間にあり日本稲のそれより高いことが明らかにされた. (3) 印度稲の生育期間は品種により3ヵ月から6ヵ月に迄及ぶが, その期間の長短にかかわらず, 葉面当り光合成能力は, 日本稲と同様に, 移植後20～30日に最大に達し以後は成熟期に向かつて漸減した. また出穂期における高まりは認められなかつた. 更に, Maha期とYala期における光合成能力の変化には特定の差異は認められなかつた. (4) 生育期間の長い品種の方が, 栄養生長期における光合成能力が若干低い傾向が認められた. (5) 日本稲の場合と同様に, 耐肥性の強い品種は弱い品種にくらべて, N施用量の増加に伴なう光合成能力の増加が大であつた. 逆に呼吸作用の増加は耐肥性の弱いものの方が大きかつた. (6) 水耕栽培した印度稲の光合成能力は, 日本稲のそれよりも低いN濃度で最大値に達することが認められた. (7) N追肥後, 印度稲は日本稲よりも光合成能力の促進は少なかつたが, 葉面積の増大が著しく大きい傾向がみられた.

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It is well known that there is remarkable difference among crops as regard to the adaptability (or durability) on acid soils. The similar relation was also observed quite distinctly among varieties of wheat and barley, as reported in the previous papers. The authors intended, as the next step, to know if those physiological characters, such as Buffer value of root juice and alminon color reaction in root tissues, are closely related with acidic-soil-durability, and might be useful as a short method of judging the suitability in breeding. The process and results are as follows. 1. Root juice was sqneezed out and filtrated from young plants of 7-leaf stage, grown on non-acidic soil, and Buffer values were measured after the method of YOSIMURA. (Table 1). The results showed that there was discernible difference among varieties, and those varieties of more durable to acidic soil held larger Buffer values than weak ones (Table 2). 2. Middle part of seminal roots were cut-off from young seedlings of 5-leaf stage grown on acidic soils in pots, and cross-sected 10μ in thickness with freezing microtome, and were dipped in alminon-reagent for 1 hour, washed with water, and then treated in ammomium carbonate solution for half an hour, and observed under microscope (Fig. 1) according the procedure after AIMI. Tissues were dyed from external to internal parts accompanying some gradation of the color. Range and deepness of the coloring differed by variety. Weak varieties showed wider and deeper coloring in general, proving more quantity of intake of alminium in soils. The authors conclude, therefere, these laboratory methods are recommendable as a short or certifying method of judging adaptability on acidic soils among materials of wheat and barley breeding.

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This study was made to research the cause of crack formation in rice kernels during wetting and drying. 1. Moisture content of rice kernels during maturation. Changes of moisture content of rice kernel during maturation are divided into three periods. In the first period, moisture content decreases physiologically with the increase of dry weight of kernel and reaches about 28% when dry weight becomes the maximum value. In the second period, moisture content of approximately 28% lasts about 10 days without any appreciable change. In the third period, moisure content decreases physically under the influence of weather. (Fig. 1) Cracks do not occur in the first and the second periods because moisture content is not affected by weather condition in these periods, whereas cracks may occur in the field during third period by weather condition. 2. Crack formation during wetting. When paddies are soaked in water, cracks occur increasingly with the progress of soaking time until moisture content of kernel reaches about 20%, then cracks gradually decrease wiht the lapse of time and almost all cracks disappear until moisture content reaches 30%. (Table 2, 3) Because, endosperms moistened over about 20% become very flexible and cracks are cemented by the pressure resulted from enforced swelling of kernels in the chaffs. The moist kernels, above about 20% in moisture contents, do not crack by wetting, for they are too flexible to be checked by the stress and the immature kernels having the soft cells which are filled insufficiently with starch do not crack by the buffer action of such cells. It is, therefore, thought that the essential conditions of crack formation are: (1) the stress set up in the endosperm by the unequal swelling as a result of uneven absorption of water; (2) endosperm hardness which is hard enough to respond to the stress. When the stress is set up in the endosperm which is hard enough, crack is formed in parallel with the short axis of the kernel alons the cell arrangement, because this direction is most irresistible against the stress. 3. Crack formation during drying. During one-pass drying, decrease of moisture is very rapid in chaffs but is very slow in kernels during the first 60 minutes, and as the time elapses, kermels are enforced to dry and inclination of moisture contents occurs within kernel as indicated by the difference between the upper halves and the lower halves of kernels as shown in Fig. 5, hence cracks are increasingly formed. On the other hand, on five-pass drying, moisture moves slowly from kernels into chaffs during tempering and moistened chaffs dry rapidly but kernels are not enforced to dry during the succeeding drying. Accordingly, disturbances in moisture distribution do not occur in kernels, and crack formation is far than one-pass drying. The cause of crack formation during drying is the stress set up by the unequal shrinking of endosperm as the result of uneven dehydration. (Fig. 4, 5) 4. Processes of hydration and dehydration of kernels. The distribution of moisture within kernels was investigated during wetting and drying to study the mode of hydration and dehydration. Hardness of any specified point within endosperm increases or decreases linearly according to decrease or increase of its moisture content, consequently, the moisture content of some points in endosperm can be calculated by measuring the hardness of that point. (Fig. 7) Moisture distribution in endosperm during wetting and drying of paddy was measured by this method. (Fig. 8, 9) Water penetrates mainly from the region around the germ into the endosperm and advances to the middle and apical regions through the peripheral region of endosporm and penetrates slowly, at the same time, from the peripheral region to the central region. Water penetration through the attachment region as well as the testa is not remarkable. Then the ventral region that lies close to the germ is moistened more rapidly than dorsal region. The mode of

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前報において, 落水処理による収量の増加は, 登熟期の見掛けの同化量の増加による事を報告したが, 収量に対する真の同化作用と呼吸作用との関係, とくに, 葉位別の問題については明らかになし得なかった. 本実験では, 常時湛水区を対照として, 早期中干区 (栄養生長の後期の落水) と晩期中干区 (幼穂の発育する期間) の二つの落水区を設け, 主として, 登熟期の葉身の機能と, 登熟との関係について調査した. 1. 各葉位の葉身のはたらきを, ガス代謝と剪葉法による稔実調査の両面から検討したところ, 大体, 同様な傾向が認められ, 常時湛水区に比べ, 中干区では, 各葉位とも葉身の乾物生産能力が高められていた. 2. 中干区では, 葉身単位面積当りの真の光合成作用が高いとともに, 呼吸作用が低く, したがって, P/R比が高い傾向を示した. また, 登熟のある時期まで, 葉の充実度もまさっていた. 3. これらのことが, 中干区で退化穎花数を減少させ, 1粒重を増加し, 上米歩合を高め, 収量の増加を来たしたものと考えた.

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This paper dealt with the results investigated on the degree of variation in the number of sterile filaments and its classificatory significance in peanut (Arachis hypogaea, L.), using 121 cultivated varieties or strains originated from various countries of the world and Japan (Table 1). Significance of classification of varieties based on the plant type was investigated by use of discriminant function evaluated by the above character and other 3 characters of varieties (Tables 3 and 4). Results and considerations obtained are as follows: 1) The rate of appearance of "10-", "9-", and "8-anthers-flower" (0, 1, and 2 in the number of sterile filaments, respectively) was characteristic of the varietal groups classified by the plant type, with one exceptional variety. "Eight-anthers-flower" appeared predominantly in all varieties examined. However, significant much higher rate of appearance of "9-anthers-flower+10-anthers-flower" (%) was observed in the erect varieties (Spanish and Valencia types), compared with that in the prostrate and semi-prostrate ones (Virginia Runner and V. Bunch types) (Table 2 and Fig. 1). No significant differences in this values were found between the 2 types in each of the above 2 varietal groups. 2) From these results, the following conclusions were derived: i) The 2 varietal groups of the cultivated peanut, i. e. the erect type and prostrate type (including the semi-prostrate type), are different markedly in the degree of variation in the number of sterile filaments, as one of the floral morphological characteristics of this plant. In other words, the characteristic presence of 2 sterile filaments has almost being stabilized in the latter varietal group than the former one. ii) It is most presumable that the androecium having no sterile filaments is most primitive and fundamental type of the androecium of this plant. And it is of great interest to find out a relationship between varietal groups and the trend of gradual decreasing and stabilization in fertile stamen number in this plant, i. e. "10→9→8" (Table 6), in connection with the assumption on degree of primitiveness or advancement of each varietal group, viewed from the "androecium-morphology". iii) More extensive studies on the "androecium-morphology" in a number of cultivated varieties and the allied species of this plant, and survey of the plant which normally have only "10-anthers-flower" may give a clue to clear up somewhat of the problems on the origin, geographic distribution, varietal differentiation, and classification of this plant. 3) Three discriminant functions, to investigate the classification of varieties based on the plant type, were evaluated by use of 4 characters: rate of appearance of "9-anthers-flower+10-anthers-flower" (%) (x₁), width of terminal leaflet (x₂), pod volume (x₃), and length of calyxtube (x₄). High significant difference (p<0.001) in mean discriminant values was recognized only between the erect varieties and the prostrate varieties (including semi-prostrate varieties), and not between prostrate and semi-prostrate, and also between Spanish and Valencia types (Fig. 2). 4) From the above-mentioned results, it appears to be reasonable to take the plant type as the primary basic character in botanical classification of the cultivated peanut varieties.

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